Electromagnetic sound reproducer



Nov. 7, 1933. s. A. SOLLIE ELECTROMAGNETIC SOUND REPRODUCER' 3 Sheets-Sheet 1 Filed July 30. 1927 INVENTOR. xi zjardfl. SoZZz'e,

BY m GHMATTORNEY Nov. 7, 1933. s. A. SOLLIE 1,934,099

ELECTROMAGNETIC SOUND REPRODUCER Filed July 30, 1927 3 Sheets-Sheet 2 INVENTOR. 8944211 A. SOZZJQ, BY (9 A TTORNEY v v Nov. 7,1933. 5. A. SOLLIE ELECTROMAGNETIC SOUND REPRODUCER 3 Sheets-Shqet 3 Filed July 30, 1927 [NI/EN 701e, ref/l. 8022A- ATTORNEY.

Patented Nov. 7, 1933 PATENT OFFICE 1,934,099 ELECTROMAGNETIC SOUND REPRODUCER Sigurd A. Sollie, Palo Alto, Calif.) assignor to Federal Telegraph Company, San Francisco, Calif., a corporation of California Application July 30, 1927. Serial No. 209,468

10 Claims. 7 (Cl. 179-1155) My inventionrelates broadly to sound repro- My invention is directed to that class of sound reproducing diaphragms disclosed more fully in letters Patent #1,63'7,119, granted to Frederick A. Kolster and Sigurd A. Sollie, July 26, 1927.

One of. the objects of my invention is to rcvide means for suspending a conical shaped diaphragm in a plane intermediatethe apex and free peripheral edge thereof in such manner that sound vibrations may be impressed upon the cone shaped diaphragm from an electromagnetic driving system. I Another object of my invention is to provide a free edge cone shaped sound reproducing diaphragm construction having means for eliminating blasting of the free peripheral edge while suspending the diaphragm intermediate the free 29- peripheral edge and the apex thereof.

" Still another object of my invention is to provide a construction of cone shaped sound reproducing diaphragm having means for centering the diaphragm within a ring structure intermediate the apex and peripheral edge thereof and suspending the diaphragm in the centered position for reciprocatory movement and the reproduction of sound from sound vibrations which are impressed upon the soundreproducing diaph s A further object of my invention is to provide a supporting member for an electromagnetic winding within the fieldof a power speaker system, wherein a metallic ring member forms both the connecting means between the coil supporting member and aconical shaped diaphragm'and also provides a closed circuitadjacent the electromagnetic winding for flattening the characteristic curve of the loud speaker system.

Other and further objects of my invention reside in the construction of the centering means for the cone shaped sound reproducing diaphragm as set forth .in the following specification by reference to the accompanying drawings, 5 wherein:

' Figure 1 is a side elevation partially in crosssection showing the constructionof the suspension means for the sound reproducing diaphragm of my invention; Fig. 2 is a front view of the stiff ening member which I provide adjacent the supporting membrane in the sound reproducer for centering the cone with respect to the membrane; Fig. 3 is a side elevation of the centering device illustrated in Fig. 2; 'Fig. 4 is an enlarged view of the free peripheral edge of the sound reproducing diaphragm of my invention; Fig. 5 is, a cross-sectional view showing a modified.ar-' rangement of centering device for the sound reproducing diaphragm of my invention; Fig. .6 is a perspective View of the centering device illustrated in cross-section in Fig. 5; and Fig. 7 is a perspective view of the construction of bobbin which carries the operating winding constitut-' ing part of the. electromagnetic driver of the sound reproducer of my invention.

In the assembly of power speakers having a conev suspended in themanner set forth in the aforesaid Letters Patent, the centering of the free edge cone shaped diaphragm towhich the actuating winding is connected in a position within the magnetic gap of the loud speaker, a number of mechanical diff culties are encountered. It 'is diificult to quickly assemble the cone shaped sound reproducing diaphragm. within the-surrounding ring structure in a plane intermediate the apex and free peripheral edge of the cone in 7 such manner that the actuating winding does not drag upon the pole faces of the field magnet system. This centering. difficulty in the assembly process may be overcome by securing the peripheral edge of the cone shaped sound reproducing diaphragm but thisexpedient involves. other difficulties which are undesirable. In theconstruction of my invention, I-provide a simplified means for accurately setting the actuating bobbin withinthe magnetic gap of the power speaker system regardless of the fact thatthe only support for the cone shaped sound reproducing diaphragm is in the plane intermediate the apex and free peripheral edge thereof; I provide a stiffened centering device which supplements the suspending membrane. The stiffeneddevice is rigid in a radial direction but is flexible in the direction of theaxis of the cone shaped sound reproducing diaphragm permitting free vibratory movement of the diaphragm. In order to secure an eff cient response over a broad range offrequencies, the

actuating bobbin which is attached to the cone shaped sound reproducing diaphragm is provided with a metallicconicalshaped connecting means which serves not only as a unit or coupling between the cone shapedsound reproducing diaphragm but also as a short circuited conductor whichintroduces such losses in the loud speaker as will produce such acharacteristic curve as will uniformily reproduce the notes over a broad range of frequencies. i

Referring more particularly tothe drawings; reference'character -1 designates a cone shaped sound reproducing diaphragmhaving a rolled pcripheral edge 2 with a stiffening ring member 3 therein. A damping member 4 is attached to the outer body of the cone for suppressing blasting, weaving, rattling, fluttering or other noises inherent in cone shaped diaphragms as set forth more particularly in Patent No. 1,775,064, granted to Ralph L. Brown. Aring structure 5 is provided for locating the cone in position with respect to the electromagnetic drivingmechanism. The ring structure 5 has an annular bead 6 formed on the edge thereof. A flexible membrane 7 is attached to the body of the cone 1 in a position intermediate the apex and'free peripheral edge thereof and is extended over the beaded edge 6 onto the cylindrical surface of the ring structure 5. The membrane '7 is secured over the ring structure 5 by means of a hoop member 8 which snugly secures the membrane 7 upon the cylindrical surface 5. In orderto rapidly and accurately center the cone with respect to the ring member 5 during the assembly'process, I provide a stiffening member 9 having a flat circular portion and a central conicalportion 10' illustrated more clearly in Figs. 2 and 3. The conical portion 10 snugly fits over the portion of the membrane 7 which is attached to the surface of the cone 1 and extends into the off-set shoulder designatedat 27 in ring structure 5. The centering device 9 is apertured at 11 (Fig.2) in such manner that the cone is free to vibrate inthe direction of the axis thereof but is rigidly centered in a radial direction. This centering means permits the bobbin 16 which is carried by coil support 12 in turn connectedthrough metallic member 14 withan inturned head 15 therein to be accurately centered within the magnetic gap of the pole pieces of the power speaker. The structure of the coil support and metallic conductor 14 is shown more clearly in Fig. '7. It will be observed that the conductor 14 provides a closed metallic circuit immediately adjacent the winding 16 for the introduction of the desired losses'for rendering the reproduction curve for the loud speaker more uniform over a wide band of frequencies; t T In Figs. 5 and 6, I have shown'the modified arrangement of centering device in the form of a radially stiffened plate 22 which fits into the shoulder 26 in ring structure 5 and is secured therein by means of ring member 23. The cen-' tering device includes flattened portion 22 apertured as represented at 24 with a central outwardly flared portion 25 for receiving the-cone shaped diaphragm. In this type of construction, a cone is shown as having a pair of apex pieces 20 and 21 secured to opposite sides of the apex with the rod member 18 projecting therefrom through which vibrations may be imparted to the cone shaped diaphragm 1 from the electromagnetic driver.

The construction of sound reproducing diaphragm described herein has been found to be extremely practical for manufacture and production, and while I have described preferred embodiments of my invention, I desire that itbe understood that modificationsmay be made and that no limitations are intended other than are imposed by the scope of the appended claims;

'What I claim asnew and desire to secure by Letters Patent of the United States is as follows:

1. A conical shaped sound r producing diaphragm, means for suspending said diaphragm for vibratory movement'alongan axis passing through the apex of said cone shapedsound reproducing diaphragm, a free peripheral edge on said diaphragm constituted by the material of said diaphragm rolled upon itself and over a stiffening ring member for defining the edge of the cone and means surrounding said cone adjacent the peripheral edge thereof for preventing excess vibration of said diaphragm.

2. In a sound reproducing diaphragm comprisinga cone shaped sound reproducing surface,

means for supporting said diaphragm from a position intermediate the apex and free'peripheral edge thereof, a stiffening ring member positioned adjacent the free peripheral edge of said diaphragm, said diaphragm being rolled over said stiffening ring member and means surrounding said diaphragmadjacent said stiffening ring for preventing excess vibration of said diaphragm.

3. Ina sound reproducer, a cone shaped sound reproducingdiaphragm, a membrane for suspending said cone shaped sound reproducing diaphragm from a position intermediate the apex and peripheral edgethereof, and means extending in a plane parallel to said membrane'for stiffening said membrane radially while enabling said membrane to freely move in a direction for permitting vibratory action of said diaphragm along an axis passing through the apex thereof.

4. A sound reproducer comprising a conical shaped sound reproducing diaphragm, aring" 5. A sound reproducing diaphragm comprising a cone shaped sound reproducing surface, a ring structure positioned intermediate-the apex of said diaphragm and the peripheral edge thereof, a flexible membrane extending from the exterior surface of said conical shaped sound reproducing diaphragm and said ring structure, and a plate member fitting over a portion of said diaphragm in said ring structure.

6. A sound reproducer including a conical shaped sound reproducing diaphragm, a ring structure, a flexible membrane extending from said ring structure and attached to said conical shaped sound reproducing diaphragm in a plane intermediate the apex and peripheral edge thereof, and a plate member having-a conical shaped portion and a radially extending portion, the conical" shaped portion of said plate member fitting over the surface of said diaphragm and'th'e radially extending-portion of said plate'member'extending parallel to said flexible membrane and fitting into said ring structure for concentrically positioning said diaphragm with respect to said ring structure.

7. A sound. reproducer including .a conical shaped sound reproducing diaphragm, a ring structure, a flexible membrane extending from said ring structure and attached to said conical shaped, sound reproducingdiaphragm in a plane intermediate the apex and peripheral edge thereofand'a plate member having a conical shaped portion and a radially extending portion, the conical shaped portion of said plate member fltting over said diaphragm, and the radially ex tending portion of said plate member connecting for centering said diaphragm concentrically withwith said ring structure, said radially extending portion having rigidity in a laterally extending plane and being flexible in the direction of the axis of said diaphragm, whereby said diaphragm may be concentrically positioned within said ring structure and freely vibratile therein.

8.111 a sound reproducer, a conical shaped sound reproducing diaphragm, means for suspending said diaphragm from a position intermediate the apex and peripheral edge thereof, an electromagnetic driving mechanism for imparting vibratory forces to said diaphragm, said mechanism including a coil support of insulating material, a winding carried by said coil support, and a conical shaped metallic member forming a coupling between said coil support and said conical shaped sound reproducing diaphragm.

9. In a sound reproducer, a conical shaped sound reproducing diaphragm, means for suspending said diaphragm from a position intermediate the apex and peripheral edge thereof, an

electromagnetic driving mechanism for imparting vibratory forces to said diaphragm, said mechanism including a coil support of insulating material, a winding carried by said coil support and a metallic member connecting said coil support to said conical shaped sound reproducing diaphragm at a position adjacent the position of suspension thereof, said metallic member having a conical portion conforming to the shape of said diaphragm, and a cylindrical portion conforming to the shape of said coil support.

10. In a sound reproducer including a conical diaphragm, a relatively rigid tubular member, an operating coil carried by said member, a conical sleeve secured to the convex side of the diaphragm and supporting said tubular member in a position extending from one end of said sleeve and enclosing the apex of the diaphragm, and flexible supporting means including flexible arms connected to the other end of said conical sleeve.

SIGURD A. soLLIE. 

